The present invention relates to a running device for farm machine and in particular for machines intended for collecting swaths on the ground of the pick-up type which are pushed by a self-propelled machine, such as a silo filler.
It is known that cultivated ground on which machines of this type have to move usually presents particularly uneven surfaces of which the hollows and bumps impart to the pick-up, during its displacement, repetitive shocks which have a detrimental effect on the integrity thereof.
In the prior state of the art, farm machines have been proposed, equipped at each of their ends with running means constituted by a front wheel and a rear wheel whose axles are connected by a rectilinear frame member articulated at its centre on the machine body, which has the effect of ensuring a xe2x80x9csmoothingxe2x80x9d of the curve of the land travelled over.
The present invention has for its object to improve the devices of this type by proposing a device which makes it possible to arrange on this type of machine wheels whose diameter is greater than that usable in the prior state of the art, which has the effect of increasing the contact surface thereof with the ground.
The present invention thus has for its object a running device for trailer-type machine, particularly a pick-up, arranged at each end thereof, comprising at least one front wheel and one rear wheel of which the axles are made integral with at least one frame member which is mounted for rotation relative to the body of the machine, about an axis parallel to that of the wheels, characterized in that this frame member is in the form of a V so that the axis of rotation of this frame member on the machine body is located below the axis of rotation of each of the wheels. Said axis of rotation of the frame member is preferably located at the level of the intersection of the two branches of the V.
The device may comprise two wheels which may for example be located in the same plane. However, it is equally possible that at least one of the wheels of one of the ends, front or rear, is not disposed in the same plane as one of the wheels of the other end.
In one form of embodiment of the invention, at least one front wheel lies outside the machine and at least one of the rear wheels lies inside, therebeneath.
In another form of embodiment of the invention, the device comprises means for adjusting the difference in height separating the axis of rotation of the frame member and the axis of rotation of a wheel. The adjusting means may be such that the frame member comprises an outer longitudinal element extending fowardly and an inner longitudinal element extending rearwardly, at least one of these longitudinal elements being provided, at its free end, with means for fixing an adjusting plate on which a hub supporting a wheel is mounted.
One of the advantages of the pick-up according to the invention is that it makes it possible to increase the contact surface of the wheels with the ground. Such an increase is due firstly to the addition of at least one second wheel. But, in addition, the present invention allows a running device to be produced in which the point of application of the effort which is transmitted to the wheels is nearer the ground that the axis of rotation of these wheels. Apart from the fact that the stability is thus improved, this results in it then being possible to mount on the machine wheels whose diameter is larger than that usable in the prior state of the art, which has the effect of increasing the contact surface of said wheels with the ground and of improving the adherence of the machine.
Furthermore, when, as shown in FIG. 1, one of the front wheels of a pick-up equipped with a running device according to the invention, encounters a small obstacle of height h, the point of application A of the efforts between the wheels and the machine body moves, for its part, by a height which is in the ratio of the corresponding lever arms, i.e. those constituted, on the one hand, by the distance of the axle of the wheel in question with the point of application A and, on the other hand, the distance of this same axle with that of the other wheel. Thus, if the supporting point lies at an equal distance between the two wheels, such a displacement will thus be equal to h/2, that is, half the height h of the obstacle.
The present invention also makes it possible to improve ground adherence of the pick-up by enabling the front and rear wheels thereof to be easily offset in the two different vertical planes. Under these conditions, it will be understood that, as the rear wheel has a different runway from that of the front wheel, it will come into contact with virgin ground since the latter will not have suffered the passage of the front wheel.